Bathtubs have been known and used for centuries. Modern bathtubs may comprise a molded shell which forms a tub enclosure having a floor and an upstanding sidewall. The shell is typically constructed of fiberglass, plastic or a similar material, or a composite of such materials. Modern bathtubs are also provided with hot and cold water valves and supply lines which are attached to a supply nozzle or nozzles. In addition, a modern bathtub will include a drain having a drain valve that may be opened to remove water from the tub enclosure. A jetted bathtub is similar to a standard bathtub, but typically includes a pump and associated plumbing which is adapted to discharge water, usually mixed with air, into the enclosure through a plurality of jet nozzles that are mounted in the sidewall of the tub enclosure.
A jetted bathtub assembly is described in U.S. Pat. No. 3,297,025. This tub assembly includes a conventional water supply including a mixing faucet and a pair of water supply lines with associated valves, and a conventional tub drain and valve and an overflow drain. The tub assembly also includes a hydrotherapy system comprising a plurality of jet nozzles which are adapted to inject a mixture of air and water into the tub enclosure. A water manifold extends around the outside of the tub enclosure and is in fluid communication with each of the jet nozzles, and a water inlet conduit extends through the wall of the tub enclosure. A pump has an inlet side to which the inlet conduit is attached and a discharge side to which the water manifold is attached. Air is provided to the jet nozzles through an air manifold which utilizes as an intake port the overflow drain conduit of the tub assembly. When water is contained in the tub enclosure, the pump can be activated to draw water from the enclosure through the inlet conduit to the pump and to discharge water through the jet nozzles into the enclosure. Air under atmospheric pressure is drawn into the air manifold by a low pressure area created within the jet nozzles when water is pumped therethrough, so that air is mixed with the water passing through the jet nozzles.
U.S. Pat. No. 6,279,177 describes a jetted bathtub which includes a water purging system to supply air pressure to the jetted circulation system of the tub to purge any standing water remaining in the system when the pump is not operating. The purging system includes an air pump and an air manifold which is connected to one or more components of the jetted circulation system. The purging system also includes a controller and a heater which is adapted to substantially heat the air flowing through the air pump and the air manifold so that warm, dry air may be provided to the jetted circulation system. If the tub is full of water when the purging system is operated, actuation of the air pump will cause pressurized air to aerate the water flowing through the jet nozzles; however, if the tub is empty, actuation of the air pump will cause air to flow through the jetted circulation system, thereby forcing substantially all of the water remaining in the system out through the jet nozzles.
U.S. Pat. No. 6,357,060 describes a jetted bathtub similar to that of U.S. Pat. No. 6,279,177, except that it includes an ozone generator that is pneumatically connected to the air pump of the water purging system. The improved purging system of this patent is adapted to provide warm, dry, ozone-treated air to the jetted circulation system.
U.S. Pat. No. 6,395,167 describes a jetted bathtub having a combination suction fixture and disposable filter assembly. The circulation system for this tub is conventional, except that the suction fixture includes a perforated faceplate which is attached to a filter housing. The filter housing is adapted to receive a disposable filter for filtering material from the water passing through the circulation system.
Bathing appliances in the nature of spas have also become commercially successful in recent years. These spas are typically constructed as a molded shell to form a water containment or tub enclosure having a footwell or floor and an upstanding sidewall. Molded within the enclosure are a plurality of therapy stations which may include seats or platforms for reclining. The shell is typically constructed of fiberglass, plastic or a similar material, or a composite of such materials. One or more pumps are usually placed under the shell to draw water from the enclosure and discharge it, usually with air, into the enclosure through a plurality of nozzles or jets of various types. The jets are usually mounted through the shell in the sidewall, and they are designed to provide a comforting or therapeutic effect to a person occupying a therapy station. Water lines are provided between the various jets, pumps and water inlet ports, and are usually comprised of PVC piping and flexible tubing. Filters and heaters may also be provided in the typical spa.
U.S. Pat. No. 5,526,538 describes a spa having both a low speed pump and a high speed pump, and a separate circulation system associated with each pump. The low speed pump continuously circulates water from the tub enclosure through a heater and back into the tub enclosure, while the high speed pump may be operated intermittently to discharge water drawn from the tub enclosure through the spa's jet nozzles. A one-way check valve keeps water from being drawn into the circulation system through jet nozzles mounted in the walls of the tub enclosure during operation of the low speed pump. However, when a user desires to employ the jet nozzles, the high speed pump can be activated to draw water out of the tub through a skimmer and suction fitting, and to discharge the water through the one-way check valve and back into the tub through the jet nozzles.